Device and method of recording information on an optical disc

ABSTRACT

A device for recording information on an optical disc so as to improve the recording quality of the information when a recording operation has just started. The recording device includes a luminous element radiating a light for recording information on the optical disc; a radiation intensity controller constantly controlling an intensity of radiation of the light radiated by the luminous element; a constant outputting unit providing a constant energy to the luminous element; a selector selectively selecting one of the outputs of the intensity of radiation controller and the constant outputting unit; wherein, the selector selects the output from the constant outputting unit during a predetermined duration from a starting time of recording the information on the optical disc, and selects the output from the intensity of radiation controller afterward.

Divisional of prior application Ser. No. 09/840,152 filed on Apr. 24,2001, now U.S. Pat. No. 6,791,923.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Application No.139091/2000, filed May 11, 2000, in the Japanese Patent Office, thedisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for recording information onan optical disc, and in particular, to a device and method of recordinginformation on an optical disc while controlling an intensity ofradiation of a light beam radiating on the optical disc so as to recordthe information.

2. Description of the Related Art

In a conventional device for recording information on an optical disc,an intensity of radiation of a light beam radiating on an optical discis fed back to maintain the intensity of the radiation of the light beamas constant regardless of a temperature variation and the like.

FIG. 1 is a block diagram of the conventional device for recordinginformation on the optical disc. In FIG. 1, an intensity of theradiation of a light beam (laser) radiating on the optical disc is fedback to maintain the intensity of the radiation of the light beam asconstant. That is, the intensity of radiation of a laser radiated from alaser luminous element 59 is monitored by a laser output monitoring unit54, a subtractor 55 compares a monitoring value output from the laseroutput monitoring unit 54 with a reference value outputted form areference voltage generator 53, and the laser driver 58 controls anoutputted driving current to conform with the two values and therebymaintain the intensity of radiation of the laser radiated from the laserluminous element 59 as constant.

Also, in the conventional recording device shown in FIG. 2, a referencevoltage generator 53 outputs a reference value and the feedback loop isstarted through self operation, thereby starting the recording (writing)operation for the optical disc, if the recording signal output from arecording signal generator 51 is varied from a low (L) level to a high(H) level.

However, a predetermined time is required until the intensity ofradiation of the light beam (laser) reaches the reference value afteroperating the feedback loop, since a response delay occurs in thefeedback loop in the related art. That is, the intensity of radiation ofthe laser is still at a value smaller than the reference value justafter the recording has started, because the feedback loop has justbegun operating. So, the recording of the information is initiallyperformed with an intensity of radiation of the light beam smaller thanthe reference value until the intensity of radiation of the light beamrises from the initial value to the reference value during thepredetermined time. Specially, the intensity of radiation of the lightbeam is smaller than that intended for recording the information whenthe recording operation has just started.

Accordingly, there is a drawback in that the intensity of radiation of alight beam radiating on an optical disc does not reach the necessaryintensity of radiation, resulting in the recording of information whichis inferior in quality by producing errors in the recording of theinformation or non-recording of the information (non-recording areas).

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a deviceand method of recording information on an optical disc, which improvesthe recording quality of the information when the recording operationhas just started.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

To achieve the above and other objects, there is provided a device forrecording information on an optical disc, comprising a luminous elementradiating a light having recording information on the optical disc; aradiation intensity controller constantly controlling an intensity ofradiation of the light radiating from the luminous element; a constantoutputting unit providing a constant energy to the luminous element; aselector selectively selecting one of the outputs of the intensity ofradiation controller and the constant outputting unit; wherein, theselector selects the constant outputting unit during a predeterminedduration from a starting time of recording the recording information onthe optical disc, and selects the intensity of radiation controllerafterward.

It is desirable that the energy provided from the constant outputtingunit to the luminous element is determined based on a testing record inthe optical disc. Typically, an optical disc drive which recordsinformation on optical discs such as CD-R and CD-RW perform a testwriting called optimum power control (“OPC”) to determine an optimalwrite power. The discs provide a testing area (OPC area). Although useof this area depends on the drive, a typical drive uses the area asfollows.

A test writing is performed at some laser power. Then, the writtensignal is read and the power dependency of the signal quality isobtained. Then, the power of best quality is selected at the optimalpower or the optimal power is calculated using extrapolation. A testingrecord in the optical disc is performed in the sequence mentioned above.Generally, the optimal power depends on the disc type and many drivesperform the OPC before recording of the information when the disc ischanged. In the present invention, a laser is driven with constantvoltage for a predetermined period of time. The temperature dependenceof the optimal power is small, but the laser character greatly changesaccording to the changing temperature. This means that the intensity ofradiation at the predetermined period varies with the temperature.Avoiding this difficulty, the OPC is performed when the temperaturevaries over the predetermined level and the constant voltage level isthen redetermined.

It is also desirable that the testing record is performed when atemperature detector equipped in the recording device detects atemperature variation.

To also achieve the above and other objects, there is provided a methodof recording information on an optical disc by radiating a lightprovided from a luminous element, the method comprising providing aconstant energy to the luminous element during a predetermined durationfrom a starting time of recording the recording information on theoptical disc; and controlling an intensity of radiation radiating fromthe luminous element to be constant afterward.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a block diagram of a conventional device for recordinginformation on an optical disc according to the related art;

FIG. 2 is a block diagram of a device for recording information on anoptical disc according to an embodiment of the present invention; and

FIG. 3 is a block diagram of a temperature detector and microcontrollerof the device for recording information shown in FIG. 2.

DETAILED DESCRIPTION

A preferred embodiment of the present invention will be described hereinbelow with reference to the accompanying drawings. In the followingdescription, well-known functions or constructions are not described indetail since they would obscure the invention in unnecessary detail.

FIG. 2 is a block diagram of a device for recording information on anoptical disc according to an embodiment of the present invention.Referring to FIG. 2, a recording signal generator 1 generates andoutputs a recording signal. In the device for recording information onthe optical disc according to the present invention, if the recordingsignal output from the recording signal generator 1 is changed from alow (L) level to a high (H) level, information recording on the opticaldisc is started.

The recording signal output from the recording signal generator 1 isinput to a wave forming unit 2 and a reference voltage generator 3,respectively. The wave forming unit 2 outputs a selection signaldepending on the recording signal. That is, if the recording signal ischanged from the L level to the H level at the time t0, the selectionsignal is also changed from the L level to the H level at the time t0and then returns to the L level after maintaining the H level for apredetermined time. The reference voltage generator 3 generates andoutputs the reference voltage representing the reference intensity ofradiation of a laser. That is, if the recording signal is varied fromthe L level to the H level, the reference voltage generator 3 startsoutputting the reference voltage.

A laser output-monitoring unit 4 detects the intensity of radiation ofthe laser output from a laser luminous element 9 which will be describedhereinafter, and starts outputting the monitoring voltage depending onthe detected intensity of radiation.

A subtractor 5 subtracts the reference voltage from the monitoringvoltage, and outputs a difference voltage depending on the subtractedresult. A constant voltage generator generates and outputs apredetermined constant voltage. A signal selector alternatively outputsthe constant voltage from the constant voltage generator 6 and thedifference voltage from the subtractor 5. The signal selector 7alternatively selects one of the constant voltage and the differencevoltage based on the selection signal output from the wave forming unit2. That is, the signal selector 7 selects the constant voltage if theselection signal becomes the H level, and selects the difference voltageif the selection signal becomes the L level.

The output of the signal selector 7 is input to the laser driver 8. Thelaser driver 8 outputs a laser driving current depending on the inputsignal. The laser luminous element 9 varies the intensity of radiationof the laser which is radiated depending on the laser driving current.Also, data for recording information on the optical disc is input to thelaser driver 8, and the laser output by the laser luminous element 9 isturned on/off by the received data.

Now, the operation of the recording device of the present invention willbe explained with reference to FIG. 2.

If the recording signal output from the recording signal generator 1 isvaried from the L level to the H level, the information recording isstarted on the optical disc. That is, the reference voltage generator 3starts outputting the reference voltage, if the recording signal isvaried from the L level to the H level. The subtractor 5 subtracts thereference voltage output from the reference voltage generator 3 from themonitoring voltage output from the laser output monitoring unit 4, andoutputs the difference voltage depending on the subtracted result.

Since the wave forming unit 2 outputs the H level for a predeterminedtime after the recording of the information has just started, the signalselector 7 selects the constant voltage output from the constant voltagegenerator 6 during the predetermined duration after the recording of theinformation has just started, and then selects the difference voltageoutput from the subtractor 5 afterward. Accordingly, the constantvoltage is input to the laser driver 8 during the predetermined durationafter the recording has just started, and then selects the differencevoltage afterward.

Next, the laser driver 8 forwards the constant driving current to thelaser luminous element 9 during the predetermined duration after therecording has just started, and forwards the driving current whichvaries depending on the difference voltage afterward. So, the laserluminous element 9 is driven by the constant driving current during thepredetermined duration after the recording has just started, and then iscontrolled by the constant intensity of radiation afterward. Thus, thelaser luminous element 9 is driven so that the laser is controlled so asto have a constant intensity of radiation after the predeterminedduration.

As described above, the intensity of radiation of the laser beamradiated by the laser luminous element 9 is not constantly controlled asa constant during the predetermined duration after the recording hasjust started, i.e., until the operation of the feedback is at a stablestate. However, errors in recording the information or the non recordingof the information can be prevented during the predetermined durationafter the recording has just started, when the constant voltagegenerated in the constant voltage generator 6 is determined in a mannerthat the intensity of radiation of the laser radiated in the laserluminous element 9 is larger than the intensity of radiation which isnecessary in recording information on the optical disc.

In the present invention, the recording of information is achieved byforming marks on the optical disc. Weak laser radiation forms anincomplete mark or a missing mark. Errors in recording, in which anincomplete mark that cannot be read correctly, and non recording of theinformation, in which there is a missing mark, due to the weakradiation, are avoided due to the fact that the intensity of radiationof the laser beam is larger than the radiation which is necessary inrecording the information on the optical disc.

Also, while the temperature within the recording device for recordinginformation on the optical disc the characteristic of the laser luminouselement 9 is varied, if the constant voltage output from the constantvoltage generator 6 is corrected depending on the temperature, theprobability of errors occurring in recording the information or the nonrecording of the information can be decreased within the predeterminedtime after the recording has just started.

The correction is performed by monitoring the laser driving current forperforming the OPC (Optimum Power Control) operation as an example.Here, the OPC is an operation for determining the optimized intensity ofradiation of the laser by performing a testing record while theintensity of radiation of the laser varies within a predetermined areaof the optical disc, as mentioned previously. At this stage, the laserdriving current for obtaining the optimized intensity of radiation ofthe laser can be detected.

The temperature may vary from an initial time. In this case, radiationmay be weak through the same level of constant voltage as the initialtime. In the present invention, the temperature is monitored, and theOPC is performed and the level of the constant voltage is redeterminedif necessary. This operation occurs before the starting of the (second,third, . . . ) recording of the information. Generally, the OPC isperformed before the recording of the information has started on theoptical disc, and if the difference of the inner temperature of therecording device from an OPC target temperature is more than apredetermined value, by monitoring the inner temperature of therecording device using a temperature detector, the OPC is performedagain. As shown in FIG. 3, a temperature detecting element 60 detectsthe inner temperature of the recording device. A microcontroller 62receives and processes the detected inner temperature to determine thedifference with the OPC target temperature. The temperature detectingelement 60 and the microcontroller 62 form a temperature detector.Accordingly, a most suitable value for the voltage generated by theconstant voltage generator 6 can be determined.

According to the present invention, neither errors in recording theinformation on the optical disc or the non recording of the information(formation of non-recording areas) occur, thereby improving a recordingquality on the optical disc after the recording has just started, sincethe intensity of radiation of the laser recording the information on theoptical disc after the recording has just started has reached thenecessary intensity.

While the present invention has been shown and described with referenceto a certain preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

1. A device for recording information on an optical disc, comprising: a luminous element radiating a laser for recording the information on the optical disc; a radiation intensity controller generating a first signal for constantly controlling an intensity of radiation of the laser radiated by the luminous element; a constant outputting unit providing a constant energy signal; a selector selectively selecting one of the first signal output from the intensity of radiation controller and the constant energy signal output from the constant outputting unit; and a laser driver driving the laser of the luminous element in response to the selected one of first signal and constant energy signal; wherein, the selector selects the constant energy signal during a predetermined duration from a starting time of recording the information on the optical disc, and selects the first signal subsequent to an end of the predetermined duration.
 2. The device of claim 1, wherein the constant energy signal provided by the constant outputting unit is determined based on a testing record in the optical disc.
 3. The device of claim 2, further comprising a temperature detector detecting a temperature variation in the device, wherein the testing record is performed when the temperature detector detects the temperature variation to be greater than a predetermined value.
 4. The device of claim 1, wherein the intensity of radiation controller comprises: an output monitoring unit which detects the intensity of radiation of the laser, to generate a monitoring signal; a reference voltage generator generating a reference voltage signal representing a reference intensity of radiation for the laser; and a subtractor which determines a difference between the reference voltage signal and the monitoring signal, to generate the first signal.
 5. The device of claim 1, further comprising: a recording signal generator generating a recording signal for recording the information on the optical disc; and a wave forming unit generating a selection signal which changes from a first state to a second state upon a change in state of the recording signal and changes back to the first state at the end of the predetermined duration; wherein the selection signal causes the selector to select the constant energy signal upon the selection signal changing to the second state and causes the selector to select the first signal upon the selection signal changing back to the first state.
 6. The device of claim 5, wherein the intensity of radiation controller begins generating the first signal in response to receiving the recording signal.
 7. A method of recording information on an optical disc by radiating a light provided from a luminous element, the method comprising: providing a constant energy to the luminous element during a predetermined duration from a starting time of recording the information on the optical disc; controlling an intensity of radiation radiating from the luminous element after an end of the predetermined duration; detecting a temperature difference in a device for recording the information on the optical disc from a target temperature; and adjusting the constant energy if the temperature difference is greater than a predetermined value, wherein the controlling the intensity of radiation comprises: monitoring the intensity of radiation to generate a monitoring signal; comparing the monitoring signal to a reference voltage to generate a difference signal; and using the difference signal to control the intensity of radiation.
 8. A method of recording information on an optical disc, the method comprising: radiating, via a luminous element, a laser for recording the information on the optical disc; generating a first signal for constantly controlling an intensity of radiation of the radiated laser; providing a constant energy signal; selectively selecting one of the first signal and the constant energy signal; and driving the laser of the luminous element in response to the selected one of first signal and constant energy signal; wherein, in the selecting, the constant energy signal is selected during a predetermined duration from a starting time of recording the information on the optical disc, and the first signal is selected subsequent to an end of the predetermined duration.
 9. An apparatus for recording information on an optical disc by radiating a light provided from a luminous element, the apparatus comprising: a constant outputting unit providing a constant energy to the luminous element during a predetermined duration from a starting time of recording the information on the optical disc; a radiation intensity controller controlling an intensity of radiation radiating from the luminous element after an end of the predetermined duration; a temperature detector detecting a temperature difference in a device for recording the information on the optical disc from a target temperature; and an energy adjuster adjusting the constant energy if the temperature difference is greater than a predetermined value, wherein the radiation intensity controller comprises: a monitor monitoring the intensity of radiation to generate a monitoring signal; and a comparator comparing the monitoring signal to a reference voltage to generate a difference signal, and wherein the difference signal is used by the radiation intensity controller to control the intensity of radiation. 